Up until 1868, Japan was a feudal society. The country was co-ruled by the Emperor, who was really just a dude with a palace and pretty much no political power whatsoever, and the Shogun, who was the guy with all the real power.
Shoguns were military leaders whose commander-in-chiefness was inherited, and who often accessorized their outfits with super-sweet and crazy-sharp swords.
And, just like in the rest of the developing world, this whole feudalism thing really didn't sit well with the masses. So in 1867, when Emperor Kōmei died and his son took over, and then a short time later the last shogun resigned his post, a bunch of like minds got together and sowed some serious seeds of change.
Those change seeds are known collectively as the Meiji Restoration, and they come with their own spiffy charter. It's called the Charter Oath of the Five Articles, and this is what it says:
By this oath, we set up as our aim the establishment of the national wealth on a broad basis and the framing of a constitution and laws.
This itty bitty charter was a huge deal for Japan. Why? Because it completely and totally changed the way Japan operated, both within its borders and outside of them. And if we really digest what each of those five points are saying, it's pretty clear why.
Gone are rules about peasants existing solely to work for and serve the ruling elite. Instead, the focus is on getting the "common people" involved and engaged in their own lives. Instead of living to meet the needs of others, now everyone can pursue their own dreams, get involved with "affairs of the state," and go out into the world and seek knowledge.
What the charter lacked in specificity, it totally made up for in inspiration.
This document laid the path for Japan to modernize, industrialize, and liberalize, and it fully set the stage for the nation to really devote some time to its quest for geographic expansion.
See, Japan isn't all that big of a country. It's made up of about 6,500 islands that are, in total, about half the size of Texas. (FYI, 97% of Japan's population lives on the four largest islands: Hokkaido, Honshu, Kyushu, and Shikoku.) In addition to being completely made up of islands, Japan is also more than 50% covered by mountains and forests.
Great for panoramic photos; bad for certain natural resources… like oil, coal, and natural gas.
Know what makes modernization and industrialization a lot easier? That's right: oil, coal, and natural gas.
And therein lies the problem.
Japan couldn't really get its modern on with no access to fossil fuel resources, so it did what other countries in similar predicaments do: it imported. In fact, it became the U.S.'s #1 oil importer for a while there.
But importing isn't as hip—or as affordable—as making stuff at home, so Japan started thinking about how it could get some of its own fossil fuel resources.
At the same time, the Meiji Restoration was having another transformative effect on the country. While military prowess had always been a big part of the culture (samurais and martial arts, anyone?), that militarism now took on a sense of urgency as Japanese leaders realized they needed to get on par with the industrialized nations of the world if they really wanted to play ball in the big leagues.
They wanted big warships and intimidating firepower. They wanted cool new weapons technology. They wanted highly trained, skilled, and effective soldiers.
In short, they wanted the biggest and bestest military in the whole wide world.
Now if we take a big bowl, and we throw Japan's desire to modernize in there, along with its predilection toward militarism and its lack of natural resources, and we vigorously stir it all together, we get a delicious, frothy meringue that goes great with fresh fruit.
Actually, that's not true. What we get isn't meringue, it's Meiji.
Emperor Meiji, that is: the namesake of Japan's 19th-century restoration and the first Emperor in centuries to have all political power concentrated underneath him and him alone. By seizing land, going whole-hog on infrastructure creation, and conscripting all male citizens into military service for at least four years at a stretch, the Meiji administration worked hard to make Japan a full-fledged member of the Modern Country Club.
And what does a modern country do, especially one short on natural resources, if not expand? The Brits had been doing it forever; France and Spain were no strangers to colonialization; even the U.S. and Russia had territories springing up all over the place. And now…
Now it was Japan's turn.
The rest of the world didn't really have too much of a problem with all of Japan's modernizing, industrializing, and liberalizing. After all, many other countries benefited from Japan's changing infrastructure and economy.
It was the geographic expansion that really stuck in the world's craw.
This caused a few Western brows to furrow, but then when Japan fought on the side of Britain and friends in World War I, it looked like all was good again. Until Japan tried to establish a post-WWI "buffer zone" (read: a Japan-controlled Korea) between it and the Russian Bolsheviks, which caused all those brows to furrow once more.
But that was just the tip of the iceberg.
The next twenty-five years would really put some strain on the Japanese-American relationship, a strain which culminated in the attack on Pearl Harbor.
When a big blow-up happens in a personal relationship, it's usually the result of a bunch of little things adding up to one huge fight. Relationships between countries are no different, as evidenced by the squabbles between Japan and the U.S. between World War I and World War II.
And there were a bunch of squabbles.
Japan may have fought on the "right side" of World War I, but its actions after the war turned all those furrowed brows from earlier into downright frowny-faces.
Let's take a few minutes to go through some of the more frown-worthy events.
The United States had been especially tense about Japan's actions ever since 1915, when Japan sent China a rather unfriendly list of ultimatums known as the Twenty-One Demands. As China's friend, the U.S. didn't really like the tone Japan was taking… and frankly, neither did China. The issue was uneasily resolved in 1919, but no one on either side was ready to forgive and forget.
In 1921, the Four-Power Treaty was enacted between the U.S., France, Britain, and Japan. It basically said that all four countries needed to sign off on any decisions made regarding the "Pacific area." The hope was that future Twenty-One-Demands-type situations could be avoided, but the pact was too vague to do much other than sit there and look official.
In 1922, Japan, Britain, France, Italy, and the U.S. signed another pact, called the Five-Power Naval Limitation Treaty, which called for a halt to the mad post-war arms building craze that had taken over the globe. It also listed specific deets on the max amount of naval armaments each country could have. Britain and America were allowed to have the most toys, France and Italy the fewest, and Japan was in the middle.
How did Japan feel about the uneven weapons allowance ratio? Not great. Here it was, the Empire of the flippin' Sun, and it couldn't even have as many things-that-go-boom as the United States, who hadn't even been a country for a hundred and fifty years yet. What kind of nonsense was that?
Then in 1923, Great Britain officially terminated its alliance with Japan. Not only was Britain growing distrustful of Japan's intentions, but it also wanted to make sure it stayed in the good graces of its bestie, the United States.
Japan, who'd already been talking with Britain about terminating the alliance, wondered why the Brits were so gung-ho to bid them adieu all of a sudden, and the distrust intensified.
The next year, the United States passed the 1924 Immigration Act. This act set limits on how many people from different countries could emigrate to the U.S., and it effectively banned the immigration of all Arabs and Asians. Other would-be immigrant groups were affected too, but none so much as the Arabs and Asians.
How did Japan feel about this anti-Asian sentiment coming from its supposed ally?
Japan was super overpopulated, even back then, and not being able to move to places like the United States was a big blow. With nowhere else to go, Japan began to eye the Chinese-controlled Manchuria as a solution to its overcrowding woes.
In 1930, our "Big Five" were at it again, making arms reduction promises to one another and signing into existence the London Naval Treaty. This bad boy dealt specifically with shipbuilding and submarine warfare, and was basically an extension of its 1922 big bro.
And once again, Japan didn't get to have as many toys as the U.S. and Great Britain.
In 1931, tired of eyeballing Manchuria, Japan decided to go ahead and just take it over. In a particularly shady act known as the Mukden Incident, a Japanese lieutenant detonated a bunch of explosives on a Japan-owned railroad track in Mukden, Manchuria...and then blamed it on China. Japan used this flimsy excuse as a premise to invade Manchuria, take it over, and set up a puppet regime that stayed there until the end of World War II. They even renamed the country Manchukuo in 1932.
How did the U.S. and other Western countries feel about this invasion? Again, not great.
It was a brutal conflict, and the reports that made their way across the sea to Western living rooms would definitely be deserving of an "R" rating for violence and disturbing content. If anti-Japanese sentiment had been swirling around below the surface before, it was definitely starting to bubble over a little bit now.
The U.S. was also kinda shocked when Japanese ultranationalists assassinated their own Prime Minister in May of 1932 and gave the military even more control over the actions of the country. "What is going on over there?" America asked itself.
And the distance between the two continued to grow.
In 1933, Japan bowed out of the League of Nations after being criticized for its whole approach to the Manchuria situation. The rest of the delegates sat in shocked silence as Japanese head delegate Yōsuke Matsuoka pffft ed at their condemnation, told them all Japan was never coming back, and sauntered out of the room.
In 1936, Japan shocked the world into silence once more when it signed a pact with Nazi Germany, of all things. This Anti-Comintern Pact was basically an anti-Soviet-communism pact, which one might think would make the democracy-loving West happy, but not when it came as a result of an agreement with icky German Nazis.
In 1937, Japan invaded China and officially kicked off the Second Sino-Japanese War. This war lasted until Japan surrendered to the Allies in 1945 and was marked by sieges, bombings, and a whole lot of civilian casualties. One of the worst atrocities, the Nanking Massacre of 1937, involved the mass murder of 300,000 Chinese civilians and soldiers, and the mass rape of many women and children all over the city. The Japanese Army even bombed the USS Panay as it tried to evacuate American citizens from Nanking; three were killed.
How did the United States react to Japan's behavior? Well, it was shocked and it was appalled, but it really didn't want to get too- too involved and end up at war. Besides, being a big fan of modernization and industrialization itself, America knew that one of the best ways to get Japan to chill out and back off was to hit 'em in the purse. In 1938 it started doing just that, implementing trade restrictions and other economic sanctions that made it harder for Japan to run its war machine. At the same time, it started slipping a little cash here and there to China to help them out.
Japan didn't much like that. It had already been hit pretty hard by the Great Depression, its people were suffering, and it's expensive to wage war.
But even though it didn't like the sanctions or the help China was getting, Japan didn't let the U.S.'s actions deter it from continuing to perpetrate some major violence.
In 1939, World War II officially broke out in Europe, and France fell to Germany a few short months later. Japan totally seized the day and moved troops into French Indochina while France was all preoccupied, pretty much taking it over completely by July of 1941.
The United States, still not anxious to go to war but also not anxious to support imperialist expansion, started issuing further embargoes against Japan, refusing to sell them certain items in hopes they'd rein in their conquest-ing.
How did Japan feel about being all embargoed like that? Not great. And the tension thickened a little more.
In 1940, Japan signed the Tripartite Pact with Germany and Italy, forming the group soon to be known as the Axis Powers. It might sound like a cool name for a band, but making sweet music was not on the agenda for this dynamic trio. World domination was, however, and they quickly drafted other countries to join their clique (some came voluntarily, others did not), all the while waging war on Europe, China, and European interests in the rest of Asia.
The United States was starting to think that this whole thing was getting out of control. They'd been pretty cool toward Japan so far, drafting sanctions and issuing wags-of-the-finger via memo when they could have gone into beastmode and declared war. They'd even stayed out of the Hitler mess in Europe, with then-wannabe-President Roosevelt promising a crowd in 1940 that "your boys aren't going to be sent into any foreign wars."
But now, with France down for the count, Great Britain fighting with everything it had, Mussolini and Hitler running rampant all over Europe, and Japan wiping the floor with China, even FDR was starting to get a little antsy. He'd already moved the U.S. Pacific Fleet from its home in San Diego, California to the American base in Pearl Harbor, Hawaii, and he'd increased national defense spending…just in case.
And no more gas, iron, or steel were being sent to Japan by the U.S…just in case.
The U.S. had also begun providing aid to the Allies in the form of ships and guns, and it had begun training those troops that supposedly wouldn't be fighting in any foreign wars… just in case.
In fact, by November of 1941, a whole heck of a lot of "just in case" had gone down in the United States.
And with good reason. The relationship between Japan and the United States had deteriorated to the point that Roosevelt had told Japan that American troops would be coming in hot if they didn't leave China alone.
What did Japan do? They said "bah" and began planning an attack on the U.S.
And on December 7th, 1941, Japan hatched that plan and Pearl Harbor was left in flames.
Looks like "just in case" happened just in time.
As heavy as the drama between Japan and the United States was, theirs wasn't the only game in town. Europe had a few things going on in the 1930s, too.
And a lot of those things started in 1933 when a charismatic young artist named Adolf Hitler was elected as the Chancellor of Germany.
Adolf had zero political experience, but he had a lot of energy, which he soon focused on amassing power and control over everything—and everyone—in Germany. In 1934, just one year after becoming Chancellor, Hitler updated his resume with another new job title: Führer of the Third Reich.
Along with new titles come new responsibilities, and for the Führer, those responsibilities were divided into two main tenets: securing that dream called Lebensraum, or additional land on which Germans could live, and preservation of the German "racial core." Achieving both of these goals would involve killing a bunch of people, especially the Jewish ones, and Hitler was A-OK with moving forward and making it all happen ASAP.
For a good look at how that panned out, we recommend checking out Shmoop's World War II timeline here. Go ahead, do it. We'll hold.
Okay, now that we're all learned up on the play-by-play, we have a much better picture of the greater context in which the whole Japan-United States drama was going down.
Suffice it to say, there were a lot of tense shoulders all over the world for a long, long time.